若x-2y+3=0.求(2y-x)^3-2(2x-4y)^2+6y-3x的值.

若2/x-1/y=3,求[y/x-y/x-y(x-y/x-x+y)]/x-2y/x的值 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 已知x-y=3,求[（x+y)(x-y)-(x-y)^2+2y(x-y)]除以的值 已知3x =2y 求x/x+y+y/x-y-y²/x²-y² (x-y)/(x+y)=3求( 3x-2y-1)/(x+y-5) 已知|x|=2,|y|=3,|x+y|=-(x+y)求x-y y=3(x-y),x=2(x-y)求x,y的值 若x-y/x+y=5,求x-y/2x+2y+5x+5y/3x-3y的值 若x+y分之x-y=3,求式子x+y分之5(x-y)—2(x-y)分之x+y的值 若x-y分之x+y=3,求式子x+y分之5(x-y)—2（x-y）分之x+y的值 若x-y=2(x+y),求代数式x-y/x+y+x+y/x-y求代数式 x+y分之x-y+x-y分之x+y 已知:y=ax的3次方+bx+3,当x=-1/2时,y=-7,试求x=1/2时,y的值 若根号x+y-3+绝对值xy+x+y-2=0,求x/y+y/x根号x+y-3+绝对值xy+x+y-2=0,求x/y+y/x x+y/2+ x-y/2=6 2(x+y)-3x+3y=24 求X Y 已知2y-x=-3,求[4y(2x-y)-2x(2x-y)]/(2x-y {(x+y)/2+(x-y)/3=1,(x+y)-5(x-y)=2.求x=?,y=? 若x+y+3=0,求2/3-2x-2y+(-x-y)^2 若3x-2y=15,3y-2x=11,求x+y 若2x-3y=0,求5x+4y/3x-2y